Replaceable blade combination for chisel blade

ABSTRACT

A replaceable blade combination for forming plows in which a matrix yoke member is utilized to secure the placeable blade. In a first embodiment the yoke member is normally held apart by a plurality of spot-weld hinges and in a second embodiment a plurality of finger hinges on the upper member of the yoke engage the adjacent edge of the lower member of the yoke.

United States Patent Hawkins 7 [s4] REPLACEABLE BLADE COMBINATION FORCHISEL BLADE [72] Inventor: Roy 1. Han/111m, Pierce, Colo. [73]Assignee: Hawkins M15, 1110., Pierce, C010. [22] Filed: Jan. 2, 1970[21] Appl. No.: 155

Related 1.1.8. Application Data [63] Continuation-impart of Ser. No.752,017, Aug.

9, 1968, Pat. No. 3,556,229.

[52] US. Cl. ..l72/720, 172/733, 172/753, 30/338, 37/141, 30611.6 [51]Int. Cl. ..A0lb 39/18 [58] Field 01 Search ..172/556, 713, 719, 720,733.

172/745, 749-751, 753, 762, 772; 37/141, 142; 30/260, 334, 336, 337,338, 349; 306/1.5, 1.6; 83/698; 101/157, 169, 154; 15/2655, 236 A;ll8/D1G. 23, 261, 413

[56] References Cited UNITED STATES PATENTS 910.985 1/1909 Beach..l72/753 922,584 5/1909 Herscher 172/753 2,503,884 4/1950 Noble 172/7203,090,140 5/1963 Trana 172/753 1,494,956 5/ 1924 Hauser et a1 ..30I3361151 3,684,032 1451 Aug. 15, 1972 2,549,229 4/1951010380111...;1...,.,r........30/338 Arden!nautumn-uni.130,338 558,0984/1896 911111.... .....172/'/ss 3,521,561 7/1970 91116161...........l01/169 556,529 3/1896 a1116w.......................1112/753$01,509 10/1093 Taylor......................1172/751 769,194 9/1904Smith...............,1........306/l.6 2,412,992 6/1949George........................37/142 2,703,938 3/19551.0011061.............. .......s1/142 3,202,226 8/1965 Carson ..n2/119FOREIGN mrems on APPLICATIONS 677,009 12/1963 Canada ..31/142 PrimaryExaminew-Robert E. Pulfrey Assistant Examiner-C. W. HanorAttorney-Wilbur A. E. Mitchell ABSTRACT A replaceable blade combinationfor forming plows in which a matrix yoke member is utilized to securethe placeable blade.

in a first embodiment the yoke member is normally held apart by aplurality of spot-weld hinges and in a second embodiment a plurality offinger hinges on the upper member of the yoke engage the adjacent edgeof the lower member of the yoke.

4 Claim, 8 Drawing Figures PHENTED 3.684.032

SHEET 1 BF 2 W 0Q lgi D M M Fig. I

INVENTOR:

Roy 1. Hawkins,

ATTORNEY PNENTEDAUB 15 1912 SHEET 2 [IF 2 I W k T1,. NM W w NM H y 0 R YBI ATTORNEY REPLACEABLE BLADE COMBINATION FOR CHISEL BLADE My inventionis a continuation-in-part of my copending application Ser. No. 752,017filed Aug. 9, 1968, entitled Replaceable Blade Combination for Duck-FootChisel, and which co-pending application has, since filling hereof,issued under date of Jan. 10, 1971, as US. Pat. No. 3,556,229.

This information relates to chisel blades generally, and in thisembodiment more particularly to tilling blades used as a part of acultivator machine, such as in connection with ground stripping in dryland farming, on dry land duck-foot chisel cultivators.

in the dry land farming art, the wheat farmer divides his fields intosuitable plots, and he plants every other one of said areas each year.The areas which are unplanted, in any given or every other year, hesummer fallows or cultivates to keep the weeds down, to preserve themoisture during the summer, and he plants those summer-fallowedalternate areas to winter wheat in the fall of that summer-fallowedyear. The alternate areas having a harvested summer wheat crop thereonare usually permitted to stand as a stubble field throughout that falland winter, to prevent soil erosion, and then those stubble areas arechisel plowed the next spring and summer-fallowed several timesthroughout the summer of that following year.

Such summer fallowing is a surface tilling or cultivating of the soil tokill the weeds and to keep the soil comparatively loose, and to therebygive the sun a chance to enrich the soil with natural nitrogen duringthat summers summer-fallowing cultivation. Such summer fallowing in dryland areas is usually done by what is called a duck-foot chisel bladetool means of cultivation, which is b a big V-shaped rigid horizontalchisel blade, which is carried by a heavy wheeled cart and pulled by aheavy tractor, to rip and loosen the ground in a horizontal plane at adepth of 6 to 8 inches below the surface. That process is usually donethree or four times, from the start of spring stubble plowing, fromapproximately May 1, to the planting season on that soil in aboutSeptember of that same year.

Said conventional V-shaped dry land chisel blades are usually made ofone piece hard rigid heavy steel, usually 6 to 8 feet wide of 75 or 100arc, or horizontal sweep between the V-sides, and are carried rigidlyhorizontally by heavy equipment to withstand the terrific force of thepressure and friction of the soil, sand and rocks through which theblade is drawn. The front cutter blade edge of that blade usually wearsout in a comparatively short time, of one or two seasons of summerfallowing use at the most. That blade is mounted and drawn inconventional manner, with its front apex V-point and chisel V-blade sideedges being at about a vertical cross-sectional to 30 upwardly extendingangle from the horizontal. Heretofore, so far as known, when the frontlower edges of the cutter blade,of such a conventionalduck-foot-V-chisel becomes worn, it is necessary to completely replacethe entire blade cutter edge of the one-piece entire chisel, by a front6 foot wide V-shaped cutter blade edge being welded thereon to replacethe worn one, and such is at a substantial cost.

it is for the purpose of overcoming the necessity of that expensivewelding replacement of the entire 6 foot wide V-shaped duck-foot chiselcutter edge, upon the front edge thereof becoming worn, that I havedeveloped this invention.

It will be understood that the heretofore conventional V-shaped dry landduck-foot chisel, so far as known, as illustrated in cross-sectionalFIG. 3, comprises a one-piece heavy frog foot or base portion 11, towhich the front one-piece V-shaped 6 foot wide chisel cutter bladeportion 12 is conventionally bolted; and, that when the lower edge 12athereof becomes worn into the condition shown in FIG. 4, then the entireonepiece 6 foot wide V-shaped cutter chisel blade 12 has to be removed,and to the lower edge 12a thereof a new V-shaped chisel blade lower edgeportion has to be welded onto that small remaining substantially squarededge 12. That is an expensive and tedious repair process.

The principle object of my invention, therefore, is to provide a novelchisel blade combination with a divisable and replaceable front lowercutter edge blade portion, so that upon a wearing thereof that a newlower cutter blade edge portion may be inserted therein, in lieu of theworn front lower cutter blade portion, by a very simple construction inco-operation with the frog foot thereof, in order to save the cost ofreplacing the entire cutter blade.

Another object of my invention is to provide such a V-shaped duck-footchisel blade with individually replaceable cutter edges for dry landfarming, wherein the entire Vblade is constructed in portions and withthe lower cutter edge portion thereof being adapted for manualreplacement in separable portions upon becoming worn, without having toweld same to the worn cutter portion and without having to replace theentire V-shaped six foot wide entire blade edge.

Another object of this invention is the provision of such a dry landchisel blade manually replaceable combination having a spring tensionedyoke portion adapted to removably hold the front cutter edge portionthereof, so that upon the blade edge portion becoming worn it may bemanually seperably removed and replaced.

A further object of this invention is to provide such a novel dry landreplaceable chisel blade combination which can be used for many yearswithout having to be discarded in its entirety, upon the cutting edgeportions becoming worn, and which will be economical of maintenance orreplacement of the cutting edge portion thereof.

Another object of my invention is the provision in such a cutter bladeof a novel spring-tensioned V- matrix or yoke adapter clamp memberadapted to removably hold the front cutter blade edge portion thereinand between spaced apart arms thereof.

A further object of my invention is the provision of a novel adapteryoke clamp for receiving and removably holding a replaceable chiselblade therein, and having overlapping arms in close proximity to eachother and hinged at one edge hereof and with a suitable cornice grooveat the other edge thereof adapted to receive a neck portion of thecutter edge portion of the chisel blade therein and for a holdingthereof by said two arms when compressed together.

Other and further objects will be apparent to those skilled in the artfrom the following detailed explanation of the preferred embodiment ofmy invention herein.

While my preferred embodiment of my novel chisel blade invention hereinillustrated and described shows a V-shaped duck-foot chisel unit, it isto be understood that such a chisel need not be of such a V-shapedconfiguration, nor do I wish to be limited in my novel replaceable bladeinvention to a farm tilling chisel tool.

In the drawings:

FIG. 1 is a reduced plan view of a tractor drawing a plurality ofconventional dry land cultivator V-shaped duck-foot chisel cultivatorUnits D.

FIG. 2 is an enlarged perspective view of one of the dry land duck-footchisel carriage units shown in FIG. 1

FIG. 3 is an enlarged vertical cross-sectional view of the duck-footchisel tool blade D, taken on the line 3 3 of FIG. 2 and looking in thedirection of the arrows.

FIG. 4 is a similar vertical cross-sectional illustration of such a dryland conventional chisel tool of FIG. 3 after several months of use,illustrating how the front leading cutter blade edge of that chisel at124 becomes so worn that its efficiency is lost and, therefore, theentire chisel I2 blade had to be repaired or replaced.

FIG. 5 is an enlarged perspective view of my novel replaceable V-shapedduck-foot chisel blade and cutter edge combination Unit D.

FIG. 6 is an enlarged vertical cross-sectional view of my novelreplaceable duck-foot V-shaped chisel blade tool combination, taken onthe line 6-6 of FIG. 5 and looking in the direction of the arrows.

FIG. 7 is a similar enlarged vertical cross-sectional view of thisembodiment of my replaceable chisel blade combination shown in FIG. 6,taken on the same line as that of FIG. 6, but being an exploded viewthereof, and with the portion 40b of the blade shown as having been wornaway and thus in need of replacement.

FIG. 8 is an enlarged vertical cross-sectional view of a modification ofmy invention.

In FIGS. 1, 2, 3 and 4, I have illustrated the conventional onepiece 6foot wide rigid V-shaped duck-foot dry land farming tool chisel blade D.Such a blade D is mounted by a fixed vertical carrying rigid frame 10 toa V-shaped rigid duck-foot horizontal base portion 11, and which latteris carried by a conventionally elevatable wheels, and is adapted to betowed by a tractor. I have shown, by a reduced diagramatic plan view inFIG. 1, how a conventional Tractor T, in the large dry land wheatfarming areas, by means of a conventional tree hitch I-I, usually pullsthree of those dry land chisel carriages at a time. Each of thoseV-shaped duck-foot chisel blade units D are usually of an overallhorizontal span of about 6 feet. In FIG. 3, I illustrated the heretoforeconventional method of having the front entire V- shaped 6 foot facecutter blade 12, of configuration illustrated, bolted to the horizontalfrog foot base 11. I further illustrated the use of that type of aconventional blade in FIG. 4, namely, there I show how. after severalweeks or months of usage, the lower edge of that entire front 6 footwide V-cutter blade 12 becomes greatly worn until there is practicallynone of it left below the plane of the frog foot 11. Thus it is n tocompletely overhaul that V-shaped front cutter blade 12 by a completeand tedious remodeling welding of a new cutter 6 foot wide V-edge cutterpiece 12 onto what is left of that old cutter piece, as shown in FIG. 4.The worn conventional blade 12 after such usage and before its repairbefore my invention is illustrated in FIG. 4.

To overcome that disadvantageous expensive repair result just explained,I have designed my novel composite and separable replaceable V-shapedduck-foot dry land cutter blade unit combination, indicated in itsentirety as D, as illustrated in FIGS. 5, 6, 7 and 8.

In my novel combination, I secure the conventional horizontal V-shapedrigid frog foot base 20 to the lower edge of the conventional verticalrigid carriage support arm 10, as before, and I provide spaced apartbolt openings 21 in the front annular portion of that base. asillustrated.

I provide a novel V-shaped matrix yoke adapter member 22, having a legportion 22a adapted to rest on the outer downwardly and forwardlyextending surface of the frog 20, having spaced openings 25 therethroughfor a bolt in each opening. The yoke member has an upper and slightlyshorter upper leg portion 22b overlapping 220, as shown in FIGS. 7 and8. leg 22!: has companion aligned openings 24 therethrough. Upper leg22b is cross-sectionally formed as illustrated for reason to beexplained. In FIG. 7 it will be noted thatl suitably weld the upperabutting edges of the upper and lower adapted clamps 22a and 22b, atvarious spaced points 30 at approximately 5 inch intervals along thelength of that juncture edge; and effecting that welding when theopposite edges of those leg clamps are temporarily held in spaced apartcondition for the purpose, as shown in FIG. 7. Thus those weld hingespots act as spring-tensioned hinges for normally holding the upper leg22 or lower leg 22a and in the open position, as shown in FIG. 7, beforethe bolt 23 is inserted in place for compressing that yoke member, topermit insert of blade portion 40, and as will be explained.

In this modification I provide a novel replaceable elongated cutterblade portion 40, of the cross-sectional configuration shown in FIGS. 6and 7. The blade 40 has a conventional transverse lower cutting edgeportion and its opposite or other edge is formed as a reduced neck 40aof wedge or cross-sectional configuration as shown, having theextrernity thereof formed thicker than the neck as a wedge head, forreason to be explained. The transverse edge 22c of the upper adapter leg22b, opposite the welded hinge spots 30, of the composite clamp 22, isformed as a cornice projection and with its outermost cornice edgethicker than its inner edge, as illustrated, so as to snugly abut andhold the wedge neck edge portion of the chisel blade 40, when my novelreplaceable blade unit is fully assembled by its bolt 23, as shown inFIG. 6. The relative parts of my adapter clamp 22 and its upper andlower legs 22b and 220, respectively cross-sectionally formed asillustrated by the FIGS. 6 and 7, are for the reasons just explained. Iprovide suitable spaced bevel-headed plow bolts 23, each in a recessedopening 24, in the upper leg 22!), to extend therethrough and throughthe opening 25 of the lower leg 22a. Each bolt is inserted through oneof speced aligned openings 21 of the frog foot 20. A suitable lockwasher 23b and nut 23c are used to hold the head 23:! of the bolt 23against the spring tension of hinges 30 of upper leg 22b on tighteningseating of that nut to hold the adapter hinged unit 22, as shown in FIG.6, and thus hold the cornice portion 22c of upper leg 22b firmly therebyonto the wedge neck 40a of the chisel blade 40. My said novel hingeclamp combination is tightly bolt held onto the frog foot 20. It is tobe noted that the upper surface of the blade portion 40 is slightlycurved as is the outer periphery of the upper leg 22b and that the twoare formed and held,by my structure ,together in a common curve arealignment when assembled as illustrated. That outer or ground contactcurvature just explained, of my chisel 40 so held, are very important,as the ground dug by the chisel blade slides there against and upwardlythereover and by that curve there is less frictional obstruction to thatearth digging movement as the blade is pushed forwardly through theground or to the left as illustrated.

My novel replaceable blade unit D, just described, is to be noted tohave certain characteristics, namely: the vertical thickness of theouter portion of upper leg 22b at its wedge 22c edge is greater than theneck portion thereof, so that thereby a downward pulling of 22b by thebolt 23 thus assures effecting a tight holding clamp of that wedgeportion 22c against the wedge neck 40a portion of the blade 40. Further,the base leg 22a, of the adapter clamp 22, projects outwardly beyond thecornice 22c portion of the upper leg 22b for the reason of therebyproviding an adequate fulcrum holding point for blade 40 so held asexplained, to assure a tight holding of blade 40 during operation of thechisel blade unit in the ground, so that pressure to the right, as illustrated in FIG. 6, on ground chiseling use of the unit, will not cause atwisting or other movement of the neck 40a under the cornice 22c of theupper leg 22b, as will be understood. That vertical cross-sectionalformation of the upper leg 22b and lower leg 22a, as illustrated, arefor the co-action purposes on use as just explained.

When it is time to replace my novel replaceable blade 40, as when itbecomes worn on use, as diagramatically illustrated by the dottedreference numeral 40b in FIG. 7, it will be observed that a loosening ofnut 23c, and thereby loosening of the bolt 23, as shown in FIG. 7, willthen permit the spring tension of the plurality of the spaced weldedhinge" spots 30 to then thereby cause a hinge raising of the entire leg22b into the position of 22b-22a as shown in that FIG. 7, and then a newblade 40 can be inserted and the bolt 23 then tightened to the positionas shown in FIG. 6.

As viewed in FIG. 5, I form the members 22 and 40, as just explained,horizontally elongated to span each side of the front V-face of theV-frog foot 20, and to abut the adjacent edges thereof, centrally at thefront of the V, as the apex line 42 of that V-duck-foot, with the frontedge abutment as a press fit abutment without any welding at that frontapex edge, for thus permitting a removal and replacement of either ofthe members 40 on either side of that apex independently of the other.

After continued operative use of my novel duck-foot chisel toolcombination Unit D, just explained, there comes a time when there is awearing away of the front cutter edges, of the lower front edge of thechisel blades 40, and which worn away portion I have indicated by dottedlines 40b in FIG. 7. With my novel combination unit D, shown in FIGS. 5,6, 7, and 8, the farmer does not have to throw away the entire chiselblade unit 40-22, when it gets in the worn condition illustrated in FIG.7, but, as a result of my invention, instead he simply loosens the nut230, of each bolt 23, on the side of the V-duck-foot, and the springtension of hat elongated yoke 22 will then spread the legs 22a and 22bthereof, as illustrated in FIG. 7. Then the old worn blade 40 can beremoved therefrom, by a slipping thereof from therebetween, and a newblade 40 can then be inserted and the nut re-tightened to hold the newblade thereby in place as in FIG. 6. The cost of my new blade iscomparatively small, in comparison to the overall cost of the heretoforerequired conventional overall welding repair job, heretofore explained,in affixing a new cutter edge portion to the V-blade as shown in FIG. 4.

Replacement of either front cutter blade 40, on either side of my novelV-shaped 6 foot wide duck-foot composite blade D of FIGS. 5, 6 and 7,for example, can be accomplished, upon release of the bolt 23, holdingthe respective yoke 22 on that side of the V-blade, without having toloosen those on the other side of the apex 42 of the V-blade, and thusproviding a simple and comparatively inexpensive replacement job for thefarmer when it is time to replace the cutting blade of either side ofthe V-blade.

In FIG. 8 l have shown a modification of my novel hinge construction ofmy novel matrix hoke member 22 of my composite unit D. In thatmodification I spot weld a plurality of spaced rigid steel projections22F, at approximately 5 inch intervals, only to the edge of the upperleg portion 22b as shown, and so those said spotwelded pieces 22b act asdownwardly extending fingers therefrom and so as to extend beyond theplane and edge of that upper leg, and so that those finger projections,upon a placing of the upper leg 22b onto the lower leg 22a, extend overthe upper vertical edge of the lower leg 22a, and without being securedto the lower leg. Thus downwardly extending fingers 22 substantiallyaccomplish a gravity hinging combination of upper and lower legs 22b and22a of my novel adapter, though without any spring tension beingaccomplished to cause a raising of the upper leg upon release of thebolt, due to the angular positioning of this composite adapter 42 asillustrated in FIG. 8, on the frog foot 20. In this modification, whichhas all other parts otherwise constructed as before, when the operatorwishes to replace a worn out blade 40, since the frog blade 20 isnormally rigidly held horizontally substantially as illustrated in FIGS.6 and 7, it will thus be seen that when the bolt is loosened,nevertheless the parts will remain substantially in their relativearrangement, by 22b being held on 22a by a gravity holding by fingerhinges 22F, on the upper edge of 220. In that loose bolt condition, theoperator may take a suitable lever, as a crowbar, and lift the corniceedge 22c side of the upper leg 22b slightly into the dotted lineposition shown in FIG. 8, and then he holds that upper leg so elevatedsufficiently until he removes the worn blade 40 and a new blade 40 istherein inserted, and then the weight of the upper leg 22b will setitself into place when the lever is withdrawn,, and the bolt and nut canthen be replaced, as will be understood.

It will be obvious to those skilled in the art that many changes andmodifications may be made in the preferred embodiments of my inventionherein illustrated, taught and described in detail; therefore, I wish tobe bound in the teaching, spirit, scope and extent of my invention onlyby the hereunto appended claims.

What I claim and desire to secure by Letters Patent 1. In a horizontalland chisel tool, in combination, a rigid frog foot secured to andcarried by an arm of a tool carrier frame, the foot having a boltopening herein, and a replaceable chisel blade unit adapted to beremovably secured to and carried by said frog foot and comprising:matrix yoke adapter clamp unit having upper and lower overlappingsubstantially parallel legs each having two parallel edges and with theedges of each leg being parallel with the edges of the other leg andwith each leg having a companion aligned opening adapted to receive abolt extending therethrough both legs, one of said pair of adjacentparallel edges of the upper and lower legs of the adapter clamp beingspringhinge-spot-welded together at a plurality of spaced spots, a boltsecuring means extending through said bolt openings and adapted toremovably secure the adapter clamp to the frog foot, and a removablecutter blade having a reduced wedge neck portion removably positionedbetween and clampingly held by the other parallel pair of edges of thelegs of the yoke adapter clamp opposite from said spring-hinge-spotsupon securement of the adapter legs to the frog foot by the boltsecuring means, and said spring tension hinges normally holding saidlegs with said other parallel pair of edges spaced apart.

2. A land chisel tool combination as defined in claim 1, and furthercharacterized by the cutter blade wedgeneck portion beingcross-sectionally wedge shaped with its thicker cross-sectional wedgedimension being outermost, and with the upper leg of the adapter clamphaving one edge formed as a protruding cornice adapted cross-sectionallyto receive said wedge shape neck portion of the cutter blade for snugabuttment holding of that leg wedge neck portion thereby and against theother leg on that wedge shape portion of the blade being insertedbetween said legs and on securement of the bolt securement means.

3. A land chisel tool combination comprising: a rigid frog foot securedto and carried by an arm of a tool carrier frame, said frog foot havinga forwardly downwardly acute angle surface with relation to the groundsurface and having a bolt opening therein, and a replaceable chiselblade unit adapted to be removably secured to and carried by said frogfoot and comprising: a matrix yoke adapter clamp unit having upper andlower overlapping substantially parallel legs each hav- 8 ing twoparallel edges and with the edges of each leg being parallel withcorresponding edges of the other leg and with each leg having acompanion aligned bolt opening extending therethrough, one edge of theupper leg being disposed in a substantially common plane with thecorresponding edge of the lower leg, the upper leg having a plurality ofspaced fingers each secured to the one edge thereof so as to extend atsubstantially a right angle thereto, said fingers extending downwardlyover said corresponding edge of the lower leg so as to act as gravityfinger hinges for hingedly holding the upper leg on the lower leg whenthe legs are overlapped loosely on the frog foot with said fingersuppermost, a bolt securing means extending through said bolt openingsand adapted to removably secure the adapter clamp to the frog foot, anda cutter blade having a wedge neck portion edge removably held by theparallel edges of the legs opposite from said gravity finger fii ahorizontal dirt chisel tool, in combination, a rigid carrier arm securedto and carried by the underside of a tool carrier frame, a rigid frogfoot base member having a bolt opening therethrough and secured to andcarried by said arm, and a horizontal replaceable chisel blade unitremovably secured to and carried by said frog foot base and comprising:a matrix yoke member having overlapping arms joined at one end by aplurality of spaced spot welds which serve as spring-tensioned hingesfor normally urging said arms into spaced apart relation, each of saidarms having an aligned bolt opening, a bolt-securing means extendingthrough said arm openings and through the openings of the frog foot basefor thereby removably securing the yoke to the frog base by therebycompressing the arms together against the spring tension of the yokemember, and a removable earth cutter blade having a portion thereofinserted between and clampingly held by the am of thespot-welded-tensioned yoke member be fore and upon securement,respectively, of the yoke to the frog base member by the bolt-securingmeans, whereby upon release of the bolt-securing means the springtension of the spot-welded yoke member causes its arms to become spacedapart for thereby automatically releasing the cutter blade portion frombetween the yoke arms.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3.684.032Dated August 15, 1972 Inventor(s) Roy I. Hawkins It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

On the cover sheet, in the ABSTRACT line 1, "forming" should readfarming Column 1, line 36, "b" should read by Column 2, line 59,"hereof" should read thereof Column 3, line 51, "illustrated" shouldread illustrate line 55, "illustrated" should read illustrate Column 4,line 3, "separable" should read separably 7 line 10, "annular" shouldread angular line 23, "adapted" should read adapter line 38, "cutting"should read cutter Column 5, line 50, "the" should read that line 66,"hat" should read that Column 6, line 33, "22" should read 22F line 57,after place, insert a comma line 58, "withdrawn-1,," should readwithdrawn, Column 7, line 4, "herein," should read therein, line 6,after "comprising:", insert a Signed and sealed this 19th day ofDecember 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PO-1050 [10-59) USCOMM-Dc 5 375-p5g U 5 GOVERNMENTPRINTING OFFICE 19.9 O-3ll-J34

1. In a horizontal land chisel tool, in combination, a rigid frog footsecured to and carried by an arm of a tool carrier frame, the foothaving a bolt opening herein, and a replaceable chisel blade unitadapted to be removably secured to and carried by said frog foot andcomprising: matrix yoke adapter clamp unit having upper and loweroverlapping substantially parallel legs each having two parallel edgesand with the edges of each leg being parallel with the edges of theother leg and with each leg having a companion aligned opening adaptedto receive a bolt extending therethrough both legs, one of said pair ofadjacent parallel edges of the upper and lower legs of the adapter clampbeing spring-hinge-spot-welded together at a plurality of spaced spots,a bolt securing means extending through said bolt openings and adaptedto removably secure the adapter clamp to the frog foot, and a removablecutter blade having a reduced wedge neck portion removably positionedbetween and clampingly held by the other parallel pair of edges of thelegs of the yoke adapter clamp opposite from said spring-hinge-spotsupon securement of the adapter legs to the frog foot by the boltsecuring means, and said spring tension hinges normally holding saidlegs with said other parallel pair of edges Spaced apart.
 2. A landchisel tool combination as defined in claim 1, and further characterizedby the cutter blade wedge-neck portion being cross-sectionally wedgeshaped with its thicker cross-sectional wedge dimension being outermost,and with the upper leg of the adapter clamp having one edge formed as aprotruding cornice adapted cross-sectionally to receive said wedge shapeneck portion of the cutter blade for snug abuttment holding of that legwedge neck portion thereby and against the other leg on that wedge shapeportion of the blade being inserted between said legs and on securementof the bolt securement means.
 3. A land chisel tool combinationcomprising: a rigid frog foot secured to and carried by an arm of a toolcarrier frame, said frog foot having a forwardly downwardly acute anglesurface with relation to the ground surface and having a bolt openingtherein, and a replaceable chisel blade unit adapted to be removablysecured to and carried by said frog foot and comprising: a matrix yokeadapter clamp unit having upper and lower overlapping substantiallyparallel legs each having two parallel edges and with the edges of eachleg being parallel with corresponding edges of the other leg and witheach leg having a companion aligned bolt opening extending therethrough,one edge of the upper leg being disposed in a substantially common planewith the corresponding edge of the lower leg, the upper leg having aplurality of spaced fingers each secured to the one edge thereof so asto extend at substantially a right angle thereto, said fingers extendingdownwardly over said corresponding edge of the lower leg so as to act asgravity finger hinges for hingedly holding the upper leg on the lowerleg when the legs are overlapped loosely on the frog foot with saidfingers uppermost, a bolt securing means extending through said boltopenings and adapted to removably secure the adapter clamp to the frogfoot, and a cutter blade having a wedge neck portion edge removably heldby the parallel edges of the legs opposite from said gravity fingerhinges.
 4. In a horizontal dirt chisel tool, in combination, a rigidcarrier arm secured to and carried by the underside of a tool carrierframe, a rigid frog foot base member having a bolt opening therethroughand secured to and carried by said arm, and a horizontal replaceablechisel blade unit removably secured to and carried by said frog footbase and comprising: a matrix yoke member having overlapping arms joinedat one end by a plurality of spaced spot welds which serve asspring-tensioned hinges for normally urging said arms into spaced apartrelation, each of said arms having an aligned bolt opening, abolt-securing means extending through said arm openings and through theopenings of the frog foot base for thereby removably securing the yoketo the frog base by thereby compressing the arms together against thespring tension of the yoke member, and a removable earth cutter bladehaving a portion thereof inserted between and clampingly held by thearms of the spot-welded-tensioned yoke member before and uponsecurement, respectively, of the yoke to the frog base member by thebolt-securing means, whereby upon release of the holt-securing means thespring tension of the spot-welded yoke member causes its arms to becomespaced apart for thereby automatically releasing the cutter bladeportion from between the yoke arms.